I am not surprised Nikon sell more DSLR than Mirrorless, they are at the early stages and the first Z series, whilst being very capable, had a number of flaws. Like Pepperberry Farm said its horses for courses. I have a first gen Fuji X-E1 with an early evf and I don't care that it isn't as good as modern blah blah, I love it, in fact I am taking it out with me shortly because it is fun to use. I could quite happily live with evf. So often performance is judged on the finest of margins and the maligned lag is something I don't even notice. There is plenty of scope for them to live side by side. Mirrorless is currently hot, so it makes sense for companies to focus on it but Nikon and Canon have not said they will stop DSLR, they are just trimming the fat. If DSLR proves to be the most durable product, then they will turn again! If I could afford it, I would love to run an X-T3 alongside my KP because they are both a joy to use and each has things the other doesn't ... And they are both gorgeous
As for bigger, better and fancier, the new Lumix S5 is smaller than its predecessor, made of plastic, has no top LED, has a poorer evf! Its almost as if the golden mirrorless goose has stopped laying eggs, or maybe it is temporarily off colour
the current climate makes judging impossible